Integrating apparatus



Filed Sept. 29, 1951 INVENTOR.

ROSWELL W. GlLBERT Patented Dec. 15, 1953 UNITED STATES PATENT OFHQE2,662,689 INTEGRATING APPARAros Roswell W. Gilbert, Montclair, N. J.,assignor to .Weston Electrical Instrument Corporation, Newark, N. L, a.corporation of New Jersey Application September 29, 1951, Serial No.248,923

3 Claims.

This invention relates to apparatu for time integrating a variablequantity with respect to time and more particularly to electricalapparatus for integrating a voltage or currentwliich varies in magnitudewith a factor such as temperature, light, etc. I I 7 Integratingapparatus of the general type contemplated by this invention is shownand cle scribed in my United States Patent Number 2,575,951, issuedNovember 26, 1951, and entitled Integrating Apparatus. V The presentinvention concerns an improved circuit arrangement whereby suchapparatus is battery operated and the drain fronithe battery is limitedtosurges of short time duration promoting long battery life. Suchimproved apparatus is particularly adapted for use in outlying areaslacking a read ily available alternating current source, and wherein theservices of an attendant are available only at infrequent intervals. Onesuch use is in normally-unattended agricultural and weather stations forthe time integration of light radiation.

An essential element of the electrical integrating apparatus is apermanent-magnet movablecoil instrument relay of relatively highsensitivity having no mechanical restoring force and so designed andconstructed that the angular velocity of the movable coil isproportional to the current or the voltage applied to the coil. Anintegrating relay of this ty e is described and claimed in my priorPatent No. 2,239,363, Integrating Apparatus, granted April 22, 1941.

An object of this invention is the provision of a battery operatedintegrating apparatus of improved structural and operatingcharacteristics.

An object of this invention is theprovision of a battery operatedintegrating apparatus in which successive contact closures of anintegrating instrument develop pulse type advances of a countingmechanism through a pair of polarityreversing relays whereby the drainimposed upon the battery occurs only for a short period of time uponcontact closure of the integrating instru= merit.

These and other objects and advantages of the invention will becomeapparent from the following specification when taken with theaccompanying drawing in which the single View is a schematic circuitdiagram of a photoelectric integrator embodying the invention.

The light sensitive element of the integrating apparatus is a photocelliii, preferably of the bar rier layer or self-generating type, that iscon-'- nectcd to the input terminals ll Such photocell 23 generates acurrent proportional to the magnitude of light striking the activesurface. The photocell current is passed through a divided shuntcomprising the resistors i2; i3 and is reversibly passed through themovable coil M of the sensitive integrating relay iii. The reversecurrent flow through the integrating relay i5 is accomplished by areversing relay it having a movable coil ll carrying the movable contact18, and a pair of stationary contacts I9, 20 that are connected directlyto the ends of the shunt resistors ll; 13 by the wires 2|, 22respectively. When the movable contact l8 engages the stationary contactii! the photocell current flows through the movable coil I 4 of theintegrating relay 15 in one direction and. such current flow is reversedupon closure of the movable contact 28 with the other stationary contact20. Since the movable contact arm l8 of the reversing relay I6 isattached to the relay coil I! closure of one or the other contact setsof the reversing relay is controlled by the direction of current nowthrough the relay movable coil. The means for reversing the current flowin the coil of the reversing relay Will be described in detailhereinbelow. It may here be pointed out that the reversing relay isprovided with mildly magnetic contacts so that the movable Contact amwin ongage one stationary contact and remain so engaged until a surge ofreverse current produces a similar engagement of the opposite contact.

I The sensitive integrating relay I5 is of the permanent magnet-movablecoil type as described in detail in my referenced United States PatentNo. 2,239,353. The instrument construction is similar tothat ofsensitive milliarnmeters or microainmeters but differs therefrom in thatthe spring connections to the movable coil l4 impose substantially notorque load on the movable system and the coil is wound on a metalframe,- or is shunted by a, resistance, which clamps the coil so thatthe angular velocity of the coil is proportional to the applied currentor voltage. The movable coil 14 oscillates in a magnetic field ro videdby a conventional permanent magnet and each nan-cycle of movement of thmovable Coll-'- tact arm 25 from one relatively fixed contact 25 to theother contact 21 (and vice versa) corre sponds to a preselected quantityof light, in foot* candle-seconds, or meter-candle-seconds, falling uponthe photocell l0. Therefore, the total quan= tity of light, for anyperiod of time, may be measured by counting the number of half=cycles orof cycles of oscillatory movement of the movable contact arm 25 of theintegrating instrument.

An electro-magnetic counting mechanism suitable for counting thehalf-cycle oscillations of the integrating relay l5 comprises a motorhaving a permanent magnet rotor 30, a field Winding 3| having aphase-shifting capacitor 32 connected in parallel thereto, and a fieldwinding 33. When the series connected field windings of the motor areenergized by a short pulse of direct current the rotor l5 advances onesalient pole. The step-by-step rotation of the rotor results in theprogressive operation of a mechanical totalizer 34 that is connected tothe rotor by the shaft 35.

The energization of the motor field windings is controlled by a secondreversing relay 40 having a movable coil 45 carrying the movable contactarm 42, and a pair of stationary contacts 43, 44. Ihis relay 40 issimilar in construction to the reversing relay I6 and is adapted toalternate contact closures in response to reverse current surgesimpressed upon its movable coil. The movable coils of both reversingrelays l6 and 46 are connected in series whereby the respective movablecontact arms simultaneously will cross over to the opposite, associatedstationary contact.

Power for operation of the device is supplied by a battery 45 acrosswhich are connected the surge capacitors 46, 4'! by the wires 48, 49,respectively. The capacitors are arranged in series, each having oneside connected to the motor field winding 3| by the wire 55. The othermotor field winding 33 is connected to the movable contact arm 42 of thereversing relay 45 by the wire 53. It will be noted that the stationarycontact 43, of the reversing relay 40, is connected to one side of thbattery by the lead 5|, and the other stationary contact 44 is connectedto the opposite side of the battery by the lead 52 joined to the lead48. Therefore, current can only fiow through the motor field windingswhen one or the other sets of reversing relay contacts are closed andthat such current flow can only be a brief surge that exists during thecharging of the surge capacitors 46, 41 since one or the other of thesecapacitors are interposed between the motor field winding and thebattery return lead.

The operation of the device will now be described starting with thecontacts of the two reversing relays l6 and 40 closed as shown in thedrawing. Current from the photocell l flows through the lead 55, thecontact arm |3 (of the relay iii), the stationary contact l9, lead 2|,resistor I2 and lead 59, returning to the photocell. This develops apotential across the resistor l2 which potential is applied to themovable coil I4 (of the relay l) through the resistor I3 and the leads56 and 58. The arm of the integrating relay, therefore, deflects towardthe stationary contact 2? at a velocity proportional to the magnitude ofthe current, or as has been explained, proportional to the quantity oflight striking the photocell surface. When the integrating relaycontacts 25, 21 close, current from the battery flows through the leads48 and 51, closed contacts 25, 21 (of the integrating relay) leads 60,6| through the movable coil 4| of the reversing relay 40, leads 62, 63and 64, through the movable coil [1 of the reversing relay l6, leads 65and 66, the current limiting resistor 61, and leads 68, 49, 5| back tothe other side of the battery. The current limiting resistor 61 has avalue such that the magnitude of the current fiow is sufiicient todis-engage the movable contact arms of the reversing relays from theirassociated stationary contacts and cross over to establish contacts withthe opposite stationary contacts. Such cross over of the reversingrelays brings the following operations into effect.

1. The current from the photocell is reversed in the movable coil of theintegrating relay I5. Such current flow now follows the path defined bythe lead 55, reversing relay contacts I8, 20, leads 22, 58, integratingrelay coil [4, leads 51, 56, resistor l2 and lead 59.

2. The closure of the contacts 42, 44 of the reversing relay 40completes a series circuit across the battery 45 such circuit comprisingthe leads 48, 52, relay contacts 42, 44, lead 53, motor field windings33, 3| leads 50, surge capacitor 41, leads 49, 5|. A surge or pulse, ofcurrent, therefore, fiows through the motor field windings and the surgecapacitor. This current pulse is of brief duration but sufiicient toproduce a rotation of the motor rotor an angular distance equal to onerotor tooth.

3. The totalizing mechanism 34 advances one unit count.

4. Sincethe current through the movable coil of the integrating relay |5has reversed direction immediately upon closure of the contacts I8, 20of the reversing relay IS, the movable arm 25 of the integrating relayimmediately leaves the stationary contact 2'! and moves toward the otherstationary contact 26. Such opening of the contacts 25, 2'! opens thecircuit to the seriesconnected movable coils of the reversing relay.Thus, it will be apparent the device operates on current pulseseiiective only upon the momentary closure of the contacts of theintegrating relay.

Upon completion of the half cycle of operation just described the powerelements of the apparatus are in the at rest or de-energized positionwith no current being drawn from the battery. The sensitive integratingrelay alone remains active, its movable coil energized by the photo cellcurrent and moving toward the stationary contact 26 at a velocityproportional to the quantity of light striking the photocell. When,finally, the integrating relay contacts 25, 26 close, current from thebattery 45 flows through the leads 48, 51, closed contacts 25, 26 (ofthe integrating relay) leads 56, 65, the movable coil I! (of thereversing relay l6), leads 64, 53, 62, the movable coil 4| (of thereversing relay 40), lead 60, the current-limiting resistor '10, andleads 49 and 5| back to the other side of the battery. It will be notedthe direction of the current flow through the movable coils of thereversing relays is now reverse to that which prevailed during theprevious half-cycle of operation. Consequently, the movable contact armsof the reversing relays cross over, or return, to the position shown inthe drawing. Such cross over of the reversing relay I6 immediatelyreverses the direction of current fiow through the integrating relay i5and its arm 25 now moves toward the stationary contact 21. The otherreversing relay, now having closed its contacts 42, 43, completes thecharging circuit through the motor field windings and the other surgecapacitor 46 said circuit comprising the lead 5|, contacts 43, 42 (ofthe reversing relay 40) lead 53, motor field windings 33, 3|, lead 50,capacitor 46 and lead 48. The resulting current pulse advances the motorrotor another tooth thereby adding another unit to the countingmechanism.

It will now be clear the counting mechanism indicates the number ofcontact closures of the sensitive integrating relay l5. Since themovement of this relay from one stationary contact to the other is knownin terms of the quantity of light falling upon the photocell, theintegrated quantity of light falling upon the photocell is obtained bynoting the total counts on the counting mechanism.

The capacitors H, l2, connected across the movable coils of thereversing relays I6, 40, respectively, serve to damp the movement ofsuch movable coils to prevent contact bounce. The resistor E3 andcapacitor i l, shown connected into the circuit by dotted lines T5, 16,introduce a small surge through the movable coil of the sensitiveintegrating relay to prevent sticking of the relay contacts as thedirection of current flow through its movable coil is reversed. Thedamping capacitors ll, 12 and the contact release circuit comprising theresistor 73 and capacitor 14, are not required for functional operationof my device but serve to promote reliable operation.

It is to be understood that the invention is not limited to theparticular light integrating apparatus herein shown and described as thecurrent or voltage delivered to the movable coil of the sensitiveintegrating relay may be a function of some variable other than lightintensity, and changes may be made in the circuits and circuitcomponents without departing from the spirit and scope of the inventionas set forth in the following claims.

I claim:

1. In apparatus for integrating an electrical quantity, the combinationwith an integrating instrument including a movable coil mounted foroscillation in a magnetic field and carrying a contact arm cooperatingwith a set of relatively fixed contacts, and a polarity reversing switchconnected between the said movable coil and the source of the electricalquantity to be integrated, of a source of D.-C. potential, a pair ofcapacitors connected in series across said D.-C. potential source, anelective-magnetic counting mechanism including a coil having one sideconnected to the common side of the capacitors, a second reversingswitch including a pair of stationary contacts individually connected toopposite sides of the 11-0. potential source and a movable contactconnected to the other end of the coil of the counting mechanism, saidsecond reversing switch being controlled by the contacts of theintegrating instrument.

2. The invention as recited in claim 1, wherein each of the reversingswitches comprises a movable coil mounted for oscillation in a magneticfield, a movable contact carried by the movable coil, and a pair ofspaced stationary contacts adapted for engagement by the movablecontact, the said movable coils of the two reversing switches beingenergized simultaneously upon closure of the contacts of the integratinginstrument.

3. The invention as recited in claim 2, in combination with a resistorand capacitor connected in series between the movable coil of theintegrating instrument and the movable contact of the second reversingswitch.

ROSWELL W. GILBERT.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,239,363 Gilbert Apr. 22, 1941 2,575,951 Gilbert Nov. 20,1951

